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LER BPM Issues and Heating Tests. S. Ecklund, for PEP-II group ( N. Kurita, N. Reeck, S. Smith, R. Johnson, S. Novokhatski, A. Kulikov ). Issues. BPM Absolute Accuracy See G. Yocky, ORM and BBA results BPM failure under high Power conditions June event with vacuum vent Heating formula
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LER BPM Issues and Heating Tests S. Ecklund, for PEP-II group ( N. Kurita, N. Reeck, S. Smith, R. Johnson, S. Novokhatski, A. Kulikov )
Issues • BPM Absolute Accuracy • See G. Yocky, ORM and BBA results • BPM failure under high Power conditions • June event with vacuum vent • Heating formula • Lab. measurements • Test buttons • Plan for future running LER BPM issues and heating tests
LER Beam Current and RF Voltage History LER BPM issues and heating tests
LER IR2 chamber Cu (HER) Button Geometry LER BPM issues and heating tests
LER IR2 BPM LER BPM issues and heating tests
LER ARC BPM LER BPM issues and heating tests
Straight BPM • R = 44.45 mm vs. 31 for LER ARC and IR2 • Expect to have ½ the power of LER ARC and IR2 BPM’s LER BPM issues and heating tests
June 2005 Event • Thermocouple T1162QUA indicates R btn falls 14 June LER BPM issues and heating tests
1162 falls 14 June, beam at (5,-2) LER BPM issues and heating tests
2022 heats up when 1162 falls LER BPM issues and heating tests
Failed BPM • PR02 1162 • LER outgoing • In HER arc-type duct • Hexagonal Cu • Burned Cable • Lower aisle side • Vac leak through center of coax LER BPM issues and heating tests
BPM absorbed Power - Assumptions • dT ~ Power ~ S ib2 f(sz) g(x,y) = Nb ib2 f(sz) g(x,y) • Assume power absorbed at one frequencyf(sz) = exp(- (wrsz/c)2) / exp(-(wrs0/c)2) • Bunch lengthening and scale with Vrf-1/2 sz = sqrt(V0/Vrf) (s0 + si ib) f(sz) = exp(-wr2 (V0/Vrf) ((s0 + si ib) /c)2 ) / exp(-(wrs0/c)2) • Position dependence from calculated signalg(x,y) ~ signal 2 LER BPM issues and heating tests
LER Bunch Lengthening with current (from Sasha Novokhatski) (s0 + si ib) LER BPM issues and heating tests
sz LER BPM issues and heating tests
f(sz) LER BPM issues and heating tests
Nb ib2 f(sz) LER BPM issues and heating tests
g(x,y) from (Steve Smith) LER BPM issues and heating tests
g(x,y) LER BPM issues and heating tests
Lab Test - BPM Heating Experiment • Used weld test chamber with two buttons • Measurement in air • Power applied to button with 25 ohm, 25 W resistor as a heater. Measured current and voltage. • Thermocouples (6) measured: • Heater resistor • Button (2) • BPM collar (normal QUA location) • BPM cable (new RGBY tc) or center pin of connector • Cu Chamber about 1 inch from BPM • Data read with laptop running Matlab code reading serial 485 module (ADAM 4019 ADC) LER BPM issues and heating tests
Lab Test Setup LER BPM issues and heating tests
Lab Test - Run 3 Data LER BPM issues and heating tests
Lab Test - Run 3 Results • Button dT / Collar dT = 15 to 18 • Button dT/Power = 9 to 14 deg C / Watt • T vs. Power not linear • Convective cooling • Radiative cooling LER BPM issues and heating tests
Summary • No clear threshold for all buttons to fall • Have a formula, but • HOM’s are a complication not included • Assumes f=7 GHz absorption in 15 mm button • Stay below parameters of June failure till buttons are improved in 2006 down. LER BPM issues and heating tests
LER Test New BPM Buttons • Installed 3 new (modified) buttons in LER during October 2005 down • Short on 15 mm button • 7 mm no insert • 7 mm with insert • Feed-through, no button • Compare with normal 15 mm button • Measured • Temperature Rise at collar • Power to Filter-Isolator (FIB) Load Resistor LER BPM issues and heating tests
Shorted 15 mm Button From Nick Reeck LER BPM issues and heating tests
7 mm – no insert From Nick Reeck LER BPM issues and heating tests
7 mm button with insert From Nick Reeck LER BPM issues and heating tests
TC Location TC T1022RA,GA,BA,YA were moved to the FIB on BPM units 1022, 1052, 1092, and 1032 LER BPM issues and heating tests
BPM 1052 7 mm, no insert LER BPM issues and heating tests
BPM 1092 7 mm, with insert LER BPM issues and heating tests
Other Normal15 mm LER ARC BPMs1012, dT = 10 deg. F LER BPM issues and heating tests
PR02 2152 New – no button dT = 2 – 3 F LER BPM issues and heating tests
Test Button Results at I = 2.2 A 7 mm button with insert is winner 200 Watt FIB Rating LER BPM issues and heating tests
Conclusion on Button Heating • Run 5B • Limit Current to 3.3 A • Limit LER RF V to 4.5 MV • Limit Orbit offset to 3 mm • Watch TC and raw signal for change • Run 6 • LER ARC – Install new 7 mm buttons • IR2 Straight - bare feed-through or smaller buttons • LER Straight should be OK with ½ power in larger chamber LER BPM issues and heating tests